Senior Congress leader P Chidambaram on Saturday said those who prize freedom above every other right must welcome the pledge of unity made by 19 political parties and supported by the Samajwadi Party.

Chidambaram's remarks came a day after leaders of 19 Opposition parties announced that they would organise joint protests across the country from September 20 to 30, and urged people to save India for a better tomorrow.

After a virtual meeting of the Opposition parties, where they stressed unitedly moving forward to defeat the ruling Bharatiya Janata Party (BJP) in the 2024 Lok Sabha polls, the leaders also put out an 11-point charter of demands before the government.

Referring to the development, Chidambaram said those who prize freedom above every other right must welcome the pledge of unity.

"Bhakts and trolls will ridicule the show of unity, but they should remember the famous words of the German Lutheran pastor Martin Niemoller. Cynics will scoff at the effort, but they will realize one day that we are fighting for the liberty of all people, including the cynics," the former Union minister tweeted.

On Friday, Congress president Sonia Gandhi urged the top Opposition leaders to rise above political compulsions to take on the BJP in the interest of the nation and start planning "systematically" to realise the "ultimate goal" of winning the 2024 Lok Sabha polls to provide a government that believes in the values of the freedom movement and provisions of the Constitution.

Gandhi gave the clarion call at a virtual meeting of leaders of 19 Opposition parties including NCP supremo Sharad Pawar and four non-Congress chief ministers -- TMC's Mamata Banerjee (West Bengal), DMK's M K Stalin (Tamil Nadu), Shiv Sena's Uddhav Thackeray (Maharashtra) and JMM's Hemant Soren (Jharkhand) -- hosted by her.

Samajwadi Party (SP) chief Akhilesh Yadav wrote a letter to the Congress president, expressing his inability to join the meeting.